LEARN + JAPANESE / Note 116 JLPT N4
Must Be the Case (に違いない)
に違いない attaches to the plain form and means “there’s no mistaking it, it must be true.” It sits at the confident end of the certainty scale, built from 違う (to differ) plus ない, literally “there’s no way it’s different.”
Yamamoto must have a lot of foreign friends.
Yamamoto must be used to moving houses.
In Real Life
Ranked by confidence, かもしれない is the weakest, “might be,” だろう sits in the middle, “probably,” はず claims a reason-backed expectation, and に違いない tops them all, a near-certain conclusion drawn from strong evidence.
If it's right by the station, it must stay open late.
If they won an award recently, they must be getting featured in magazines and on TV a lot.
In Real Life
な-adjectives and nouns attach directly with no だ, 元気に違いない, 田中さんに違いない, the same pattern as はず and のに. ありません politely softens ない at the end, in casual speech に違いない alone works fine.
Vocabulary
| Japanese | English |
|---|---|
| foreigner | |
| moving house | |
| to get used to | |
| TV program | |
| aimed at students | |
| private room | |
| to win an award | |
| magazine | |
| to introduce, feature | |
| from now on | |
| increasingly | |
| daycare | |
| population | |
| to decrease | |
| tax | |
| conviction, certainty | |
| evidence | |
| no room for doubt | |
| to conclude firmly | |
| obvious, clear |